A collaborative strategy for elevated reduction and immobilization of Cr (VI) using nano zero valent iron assisted by schwertmannite: Removal performance and mechanism

作者：Xie, Yingying; Lu, Guining^*; Tao, Xueqin; Wen, Zhen; Dang, Zhi

来源：Journal of Hazardous Materials, 2022, 422: 126952.

DOI：10.1016/j.jhazmat.2021.126952

• Schwertmannite
• Chromium(VI)
• Nano zero valent iron
• Reduction
• Kinetics

A novel collaborative strategy for enhanced removal of Cr(VI) using nano zero valent iron (nZVI) assisted by schwertmannite (Sch) with two synthesis methods was designed. Batch experiments demonstrated that nZVI/ Sch-AP (synthesized by abiotic precipitation of Fe3+ species) exhibited excellent removal performance for Cr (VI) than nZVI/Sch-CO (synthesized by chemical oxidation of Fe2+ species). The results indicated that the removal efficiencies of Cr(VI) by nZVI/Sch-AP and nZVI/Sch-CO were highly pH-dependent and achieved to be 99.99% and 98.01% under the optimal conditions of 10 mg L-1 Cr(VI) concentration, a pH of 6.3 and a Fe(0)/Cr (VI) molar ratio of 12. But nZVI/Sch-AP emerged greater k of 0.1097 min(-1) than that of nZVI/Sch-CO (0.0485 min(-1)). Humic acid exhibited promotion effect on the Cr(VI) removal in low concentration of 1 mg L-1. Results of XRD and XPS demonstrated that alpha-FeOOH was the dominant products in both incubations of nZVI/Sch-AP and nZVI/Sch-CO, accompanied with FeCr2O4 and Cr-Fe mixed (oxy)hydroxides, and gamma-FeOOH was found alone in the incubations of nZVI/Sch-CO. We proposed a consecutive and simultaneous process involving surface absorption-reduction and co-precipitation/immobilization for the removal. This study provides new insights into the elimination of Cr(VI) from wastewater by nZVI/Sch, especially in acid mine drainage.

• 单位
  韩山师范学院; 仲恺农业工程学院